I'm considering setting up a Lustre cluster system for our XEN virtual
machines as shared storage, mainly for high availability on our XEN
VPS servers.

Does anyone use Lustre in a production environment?
What is your opinions / experiences with it?

One of the main reasons I'm looking at using Lustre is that we have a
few older machines, of different specs that I want to use for storage
purposes. i.e. I don't want to use proprietary, or matching hardware
if I don't want to. Many of these machines are still in good standing
and of good spec (3.2Ghz PIV + HT & 4GB RAM, Core2Duo + 4GB RAM,
single XEON + 4GB RAM, dual core Atoms, etc) Will this work?